This project involves investigations of rhodopsin bleaching through both model compound and native pigment studies. Primary emphasis is in determining the nature of the primary step, rhodopsin yields bathorhodopsin, and the last step thought to be important in the visual transduction mechanism, metarhodophin I yields metarhodopsin II. The primary step has been studied through model compound investigations while meta I-meta II studies have involved bovine rhodopsin investigations. Improved kinetic techniques should lead us to the ability to study other transitions, precursors to metarhodopsin I, with sufficient accuracy to make significant conclusions about the nature of visual transduction.